SHARED CHANNEL MASKS IN ON-PRODUCT TEST COMPRESSION SYSTEM

摘要

A semiconductor chip includes a first mask logic. The first mask logic includes a first mask and a second mask that mask a respective first scan channel output and a second scan channel output. The first mask logic includes at least three enable pins that receive respective enable signals. The three enable signals produce a channel mask enable encode. The first mask logic includes a first memory that stores a first channel mask enable decode for the first mask and a second memory that stores a second channel mask enable decode for the second mask. The first mask logic includes a first comparator and a second comparator. The first and second comparator compare the respective channel mask enable decodes to the channel mask enable encode. The comparators signal respective masks to mask the respective scan channel when the respective channel mask enable decode matches the channel mask enable encode.

主权项

1. A method of masking scan channels in a semiconductor chip, comprising
storing, in a first memory of a first mask logic, a first channel mask enable decode for a first mask that masks a first scan channel of a circuit under test; storing, in a second memory of a first mask logic, a second channel mask enable decode for a second mask that masks a second scan channel of the circuit under test; receiving at least three channel mask enable signals, a first channel mask enable signal on a first channel mask enable pin, a second channel mask enable signal on a second channel mask enable pin, and a third channel mask enable signal on a third channel mask enable pin, wherein the first, second, and third channel mask enable signals produce a channel mask enable encode; comparing with a first comparator the first channel mask enable decode to the channel mask enable encode; comparing with a second comparator the second channel mask enable decode to the channel mask enable encode; masking the first scan channel with the first mask when the first channel mask enable decode matches the channel mask enable encode; and masking the second scan channel with the second mask when the second channel mask enable decode matches the channel mask enable encode.